1. Field of the Invention
This invention relates to a paper detecting apparatus of an electrophotographic processor which saves product cost by enabling total sensing of paper loading and paper transporting in a paper cassette with one sensor.
2. Prior Art
Generally, electrophotographic processors, such as printers, facsimiles, and photocopiers, which use normal recording paper, are provided with a paper supply cassette 110 (FIG. 1) which is provided with a paper support 112, one side thereof being resiliently supported by a compressed coil spring 111, and a finger (not shown) which separates paper into single sheets.
The topmost paper among the paper loaded on the paper support 112 is picked up by the frictional force of a pick-up roller 120, and the paper picked up is transported to the developer 140 by a transport roller 130 and numerous idle rollers 131-133, and while the paper is passing through the developer, an image is produced by a photosensitive drum 141, picture convey roller 142, and laser scanning unit 150.
Then, toner is fixated by a heating roller 161 and a compression roller 162 and the image is completely produced on the paper, and the paper with the image produced thereon is ejected to the outside by being passed through a transport roller 170 and a paper ejection roller 180.
The paper usually starts off at point A and is ejected at point D. However, if the cover 190 is open, the paper does not pass through the paper ejection roller 180 and instead starts at point A and is ejected at point C.
On the other hand, in an electrophotographic processor, independently from the automatic paper transporting structure composed as the above, a paper tray (not shown) installed in a removable manner and used for manual paper supply may be employed.
Therefore, during manual paper supply, the paper is supplied at point B and is ejected at point C or D.
The path between the transport roller 130 and the other transport roller 170 is a shared paper transport path.
In addition, in an electrophotographic processor, there are provided various sensors for sensing respective sections, and an exemplary sensor among these sensors is the paper detecting apparatus. As the paper detecting apparatus, there are the sensor for sensing whether paper has been loaded within the paper cassette, and the sensor for sensing the paper transport state.
Here, the sensor for sensing the paper loading senses whether there is paper loaded on the paper support and outputs this data to a controller with a predetermined signal, and if it is determined that there is no paper loaded, the controller outputs error and warning messages so that the user may provide paper.
The sensor for sensing paper transport state senses whether the picked up paper has reached the printing location and senses the initiation time (position) of printing, and if the picked up paper is unable to reach the sensor location within a certain amount of time after paper pickup, it recognizes this as JAM 0, and if the picked up paper is unable to pass through the sensor location within a certain amount of time, it also recognizes this as JAM 1.
However, according to the conventional paper detecting apparatus composed as the above, because the sensor for sensing paper loading and the sensor for sensing paper transport state are provided separately, there is an undesirable problem in the aspect of economic inefficiency of the product.